Deregister iMessage online

If you don't have access to your iPhone, you can deregister iMessage online. After you complete deregistration, your phone number is removed from iMessage services. You should be able to receive text messages right away but it might take a few hours for some Apple devices to recognize that you're not using iMessage when they send you a message.

If someone sends an iMessage to your Apple ID, you'll get it on your other Apple devices. If someone sends a text to your phone number, you'll get the message only on your phone.